/*
* Conditions Of Use 
* 
* This software was developed by employees of the National Institute of
* Standards and Technology (NIST), an agency of the Federal Government.
* Pursuant to title 15 Untied States Code Section 105, works of NIST
* employees are not subject to copyright protection in the United States
* and are considered to be in the public domain.  As a result, a formal
* license is not needed to use the software.
* 
* This software is provided by NIST as a service and is expressly
* provided "AS IS."  NIST MAKES NO WARRANTY OF ANY KIND, EXPRESS, IMPLIED
* OR STATUTORY, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTY OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, NON-INFRINGEMENT
* AND DATA ACCURACY.  NIST does not warrant or make any representations
* regarding the use of the software or the results thereof, including but
* not limited to the correctness, accuracy, reliability or usefulness of
* the software.
* 
* Permission to use this software is contingent upon your acceptance
* of the terms of this agreement
*  
* .
* 
*/
/*******************************************************************************
* Product of NIST/ITL Advanced Networking Technologies Division (ANTD).        *
*******************************************************************************/
package gov.nist.javax.sdp.fields;
import gov.nist.core.*;
import javax.sdp.*;

/**
* Attribute Field.
*
*@version  JSR141-PUBLIC-REVIEW (subject to change).
*
*@author Olivier Deruelle <deruelle@antd.nist.gov>
*@author M. Ranganathan   <br/>
*
*
*
*/
public class AttributeField extends SDPField implements javax.sdp.Attribute {
	protected NameValue attribute;

	public NameValue getAttribute() {
		return attribute;
	}

	public AttributeField() {
		super(ATTRIBUTE_FIELD);
	}
	/**
	* Set the attribute member  
	*/
	public void setAttribute(NameValue a) {
		attribute = a;
		attribute.setSeparator(Separators.COLON);
	}

	/**
	*  Get the string encoded version of this object
	* @since v1.0
	*/
	public String encode() {
		String encoded_string = ATTRIBUTE_FIELD;
		if (attribute != null)
			encoded_string += attribute.encode();
		return encoded_string + Separators.NEWLINE;
	}

	public String toString() {
		return this.encode();
	}

	/** Returns the name of this attribute
	* @throws SdpParseException if the name is not well formatted.
	* @return a String identity or null.
	*/
	public String getName() throws SdpParseException {
		NameValue nameValue = getAttribute();
		if (nameValue == null)
			return null;
		else {
			String name = nameValue.getName();
			if (name == null)
				return null;
			else
				return name;
		}
	}

	/** Sets the id of this attribute.
	 * @param name  the string name/id of the attribute.
	 * @throws SdpException if the name is null
	 */
	public void setName(String name) throws SdpException {
		if (name == null)
			throw new SdpException("The name is null");
		else {
			NameValue nameValue = getAttribute();
			if (nameValue == null)
				nameValue = new NameValue();
			nameValue.setName(name);
			setAttribute(nameValue);
		}
	}

	/** Determines if this attribute has an associated value.
	 * @throws SdpParseException if the value is not well formatted.
	 * @return true if the attribute has a value.
	 */
	public boolean hasValue() throws SdpParseException {
		NameValue nameValue = getAttribute();
		if (nameValue == null)
			return false;
		else {
			Object value = nameValue.getValueAsObject();
			if (value == null)
				return false;
			else
				return true;
		}
	}

	/** Returns the value of this attribute.
	 * @throws SdpParseException if the value is not well formatted.
	 * @return the value; null if the attribute has no associated value.
	 */
	public String getValue() throws SdpParseException {
		NameValue nameValue = getAttribute();
		if (nameValue == null)
			return null;
		else {
			Object value = nameValue.getValueAsObject();
			if (value == null)
				return null;
			else if (value instanceof String)
				return (String) value;
			else
				return value.toString();
		}
	}

	/** Sets the value of this attribute.
	 * @param value the - attribute value
	 * @throws SdpException if the value is null.
	 */
	public void setValue(String value) throws SdpException {
		if (value == null)
			throw new SdpException("The value is null");
		else {
			NameValue nameValue = getAttribute();
			if (nameValue == null)
				nameValue = new NameValue();
			nameValue.setValueAsObject(value);
			setAttribute(nameValue);
		}
	}
	
	/**
	 * Allow for null value when setting the value.
	 * 
	 * @param value -- can be null.
	 */
	
	public void setValueAllowNull(String value)  {
		NameValue nameValue = getAttribute();
		if (nameValue == null)
			nameValue = new NameValue();
		nameValue.setValueAsObject(value);
		setAttribute(nameValue);
	}

	public Object clone() {
		AttributeField retval = (AttributeField) super.clone();
		if (this.attribute != null)
			retval.attribute = (NameValue) this.attribute.clone();
		return retval;
	}
	
	public boolean equals(Object that ) {
		if ( ! (that instanceof AttributeField)) return false;
		AttributeField other = (AttributeField) that	;
		return other.getAttribute().getName().equalsIgnoreCase(this.getAttribute().getName()) &&
				this.getAttribute().getValueAsObject().equals(other.getAttribute().getValueAsObject());
	}
}
